Shooting bow with springback compensation

ABSTRACT

A shooting bow is employed for shooting in sporting events and for shooting game. The shooting bow includes a main part, arms, convex in the direction of shooting, and pulleys, fastened to free tips of the arms. A bowstring passes via the pulleys, and a frame mounts the main part and a trigger mechanism. On the frame there are fastened a guide of a carriage, made up with a track, a groove for the bowstring and cutouts. The number of cutouts corresponds to the number of fletchings of an arrow. The arms are made so that the total impulse of the &#34;arms-pulleys&#34; and &#34;arrow-carriage&#34; systems, at each instant of arms straightening, approaches zero.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a shooting bow that can be used fortarget or game shooting.

2. Description of the Related Art

Known are technical solutions, similar to the present one, for instance,a bow for shooting, used in hunting and in sporting events, comprising aframe, arms, disposed at a small angle relative one to another, havingeccentric rollers at their tips, utilized to redistribute the bow forces(see U.S. Pat. No. 4,976,250, date of publication--Dec. 11, 1990).

The bow features a soft springback due to a parallel disposition of thearms; however, its shape does not provide for springback compensationduring shooting and the bow is displaced backwards and upwards, whichhas a poor effect on the accuracy of hits. Besides, since the bowstringthrusts against the arrow tail piece, the arrow shaft is subjected tocompression and, as a result, in the process, the amplitude of the arrowself-oscillations increases, which, in turn, reduces the range andaccuracy of a hit.

There is also a prior art shooting bow for target shooting, comprisingarms, attached to the central element and convex in the direction ofshooting, pulleys, a bowstring, manufactured in the form of two endspans and one middle span, a frame and a trigger mechanism (see U.S.Pat. No. 4,879,987, publication date--Nov. 14, 1989).

This prior art shooting bow, according to the technical solution, ismade compact, but features the drawbacks of the foregoing bow.

SUMMARY OF THE INVENTION

The purpose to be achieved in the course of designing a new structure ofa shooting bow has consisted of ensuring improved accuracy, increasingthe range of shooting with a similtaneous decrease of weight of saidshooting bow as well as creating more comfort for the bowman.

The purpose of the invention is to increase the accuracy of shootingwith a simultaneous decrease of the bowman's contribution to the resultof a shot, to decrease the weight of said shooting bow as well as toincrease the effective range of shooting.

The purpose is achieved thanks to including a carriage into the priorart shooting bow, disposed on the bowstring. The carriage ismanufactured with cutouts, located on the front surface thereof, thenumber of which corresponds to the number of arrow fletchings, and witha longitudinal track on the bottom and a groove for the bowstring. Atthe same time, the lower edges of the exit holes of the groove arepositioned below the upper surface of the longitudinal track of thecarriage, the arrow head contains fletchings with cutouts in the rearpart, able to enter respective cutouts of the carriage, the tail pieceof the arrow is made tapering, and the frame is made up with a carriageguide, with a horizontal slit in the forward part and a slot, in whichthe arrow guide is mounted, with the end spans of the bowstring passingvia the horizontal slit in the frame. The carriage is manufacturedmovable along the carriage guide, the distance between which and theupper surface of the longitudinal track of the carriage being greaterthan the diameter of the arrow. The point of locking the arrow in thecarriage is located in front of the centre of gravity of the arrow,whereas the width of the arrow head is smaller or equal to the width ofsaid slot in the frame of the shooting bow and greater than the diameterof the arrow shaft. The profile of said puleys is preferably designed tomeet the condition: ΔS₁ =KxΔS₂ where:

ΔS₁ is a displacement of the centre of mass M₁ to position M₁ ' of thesystem "arms-pulleys";

ΔS₂ is a displacement of the centre of gravity M₂ to position M₂ ' ofthe system "arrow-carriage";

K is a constant for each specific shooting bow and for each instant inthe course of straightening of the arms, which makes a relation: ΔS₁/ΔS₂, while the arms satisfy the condition, when the total impulse ofthe systems "arms-pulleys" and "arrow-carriage", that acts on the mainpart at the point the arms are attached thereof, at each instant ofstraightening of the arms, approaches zero.

Additionally, the end spans of the bowstring are made bifurcated, themiddle span is made up with swellings, and the arrow is furnished withstabilizers, disposed on the fletchings of the arrow head at an angle of0°to 20° to the arrow axis, with a space between the inner edges of twoadjacent stabilizers in the direction perpendicular to the plane of armsbeing greater than the diameter of the bowstring. At the tips of thearms a pulling cord is attached an elastic rope, secured to the frame.Due to the introduction of the structural elements into the shootingbow, according to the invention, the accuracy of shooting increases, therange of shooting rises and the weight of the shooting bow goes down.

DESCRIPTION OF THE DRAWINGS

The present invention is illustrated by diagrams, which depict thevarious features of the invention:

FIG. 1a is a general view of the shooting bow according to theinvention.

FIG. 1b is a longitudinal section of the shooting bow.

FIG. 1c is a shooting bow carriage.

FIG. 1d is a springback compensation diagram of the shooting bow.

FIG. 2a is a general view of an embodiment of the shooting bow.

FIG. 2b is a longitudinal section of the embodiment of the shooting bowaccording to FIG. 2a, and

FIG. 2c is a shooting bow arrow.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The invention, according to FIGS. 1a, 1b and 1c, comprises a main part(1), arms (2), pulleys (3), a bowstring (4) consisting of two end spansand one middle span, a frame (5), a trigger mechanism (6), a carriage(7), a carriage guide (8), an arrow guide (10), with the arms (2),mounted on the main part (1), convex in the direction of shooting andwith pulleys (3), disposed at their tips. The bowstring (4) is passedvia the pulleys (3). The main part (1) is mounted on the frame (5),manufactured with the trigger mechanism (6), with the carriage guide(8), with a horizontal slot (not designated), located in its forwardpart, through which the end spans of the bowstring (4) are passed andwith a slot (11), in which the arrow guide (10) is disposed. Thebowstring (4) mounts the carriage (7), made up with cutouts (12),located on its front surface (13), the number of which corresponds tothe number of fletchings (14) of the arrow (9), entering the carriage(7), with a longitudinal track (15), disposed on its bottom part and agroove (16) for the bowstring (4), the lower edges (17) of exit holes(18) of which are disposed below the upper surface (19) of thelongitudinal track (15) with the carriage made movable along thecarriage guide, a distance between which and the upper surface of thecarriage longitudinal track being greater than the diameter of the arrowthat is furnished with a head (20), having the fletchings (14), each ofwhich is manufactured with a cutout (21) and with a tapered tail piece(22). The point of the arrow fixation in the carriage is in front of thecentre of gravity of the arrow, while the width of the arrow head issmaller or equal to the width of the slot in the frame of the shootingbow and greater than the diameter of the arrow shaft, with the profileof the pulleys striving to satisfy the condition ΔS=KxΔS₂, where:

ΔS₁ is a displacement of the centre of gravity of mass M₁ to position M₁' of the system "arms-pulleys";

ΔS₂ is a displacement of the centre of gravity of mass M₂ to position M₂' of the system "arrow-carriage";

K is a constant for a specific shooting bow and for each instant ofstrightening the arms, which is determined from the relation: ΔS₁ /ΔS₂.

The arms satisfy the condition when the total impulse of the systems"arms-pulleys" and "arrow-carriage" that act on the main part, at thepoint of the arms fixation to it at each instant of arms straightening,approaches zero.

The invention according to FIG. 1a operates as follows: when arming, itis required to draw the bowstring (4) towards the bowman until it iscaught by its trigger mechanism (6). Then, the arrow (9) is taken by itsshaft to introduce it into the slot (8) of the frame (5). As soon as thearrow head occupies a position ahead of the carriage (7), the arrow isdisplaced upwards and backwards and, in the process, the cutouts (21)will enter the cutouts (12) of the front surface (13) of the carriage(7), while the shaft enters the arrow guide (10). The described armingprocedure is the safest, since the hand of the bowman does not touch thehead of the arrow. When shooting, the bowman releases the bowstring (4).In the process the arms sharply straighten up, imparting a requiredvelocity to the arrow, and since the arms (2) are bent in the directionof shooting, the total impulse of the systems "arms-pulleys" and"arrow-carriage", acting upon the main part at the point of the armsattachment to it, at each instant of arms straightening, approacheszero.

In this way the springback is compensated for. To provide for a fullequality of impulses at each instance, use is made of pulleys (3) with aprofile striving to satisfy the condition: ΔS₁ =KxΔS₂, presented in FIG.1d, where:

S₁ is a displacement of the centre of mass M₁ to position M₁ ' of thesystem "arms-pulleys";

ΔS₂ is a displacement of the centre of mass M₂ to position M₂ ' of thesystem "arrow-carriage";

K is a constant for each specific shooting bow and at each instant inthe course of the arms straightening, which is determined from therelation K=ΔS₁ /ΔS₂.

Because the arrow shaft (9) is shorter than the distance from the frontedge of the arrow guide (10) to the carriage (7) in the forwardposition, said arrow is disconnected from the shooting bow immediatelyafter the straightening of the arms and the developed displacement ofthe shooting bow does not deflect said arrow from the desired direction.In this case there is practically no angle of propelling and thereforethe accuracy of shooting does not depend on the constitution of thebowman and his skills in uniform shooting bow levelling. The range ofshooting is increased thanks to the possibility of utilizing morepowerful arms (2) with no increase in the springback and no drop in theaccuracy of shooting and because the arrow, the shaft of which issubjected to tension, can be made thinner than usual (4 to 5 mm), whichimproves the ballistic coefficient and preserves the velocity of thearrow in flight. Due to the fact that the centre of gravity of saidarrow is displaced forwardly through a maximum distance, the effect ofatmospheric disturbances (wind) on the arrow is reduced, which increasesthe accuracy of shooting.

A device depicted in FIGS. 2a and 2b is an embodiment of the invention,shown in FIG. 1a, and comprises a main part (1) that mounts arms (2),convex in the direction of shooting, having pulleys (3) at their tips,through which a bowstring is passed, consisting of two end spans and onemiddle span, designated by the refernece number (4) in the drawings.

The main part (1) is mounted on a frame (5) with a trigger mechanism(6). In this case, the end spans of the bowstring (4) are manufacturedbifurcated, the middle span of the bowstring is provided with swellings(22) and the arm (2) tips carry a pulling cord (24), mounted along withan elastic rope (25), secured to the frame (5). Said frame (5) is madeup with an arrow guide (10), whereas the arrow, depicted in FIG. 2c, ismanufactured together with stabilizers (23), mounted on the fletchings(14) of the arrow head (20), the distance between the inner edges of twoadjacent stabilizers, in the direction perpendicular to the plane ofarms being greater than the diameter of the bowstring.

The operation of the device according to FIG. 2a is carried out asfollows. When aiming the shooting bow, the pulling cord (24) is steppedon by a foot and the bowstring (4) is drawn backwards. In the process,thanks to bending of the pulling cord (24), the total stroke for armingis increased, and an effort to draw the bowstring (4) is reduced. Withthe bowstring (4) caught, the trigger mechanism (6) lets off the pullingcord (24), which is taken backwards with the aid of the elastic rope(25). Afterwards, by taking the arrow by its stabilizer (23), the arrowis positioned in the arrow guide (10), until it is in contact with thebowstring (10) between swellings on the bowstring (22). When shooting,the shooting bow arms straighten up and the arrow is in contact onlywith the bowstring (4); in the process, the effect of the framedisplacement is removed because of a distance, between two adjacentstabilizers (23) in the direction perpendicular to the plane of thearms, being greater than the diameter of the bowstring and the end spansof the bowstring being made bifurcated.

The description set forth above of the shooting bow embodiment isoptimal, as its frame is short, the weight is small and the drawingforce, applied to the bowstring, is reduced. The shooting bow provides,also for a high accuracy and a considerably effective range of shootingas well as no dependence of the result of shooting on the levellingprocedure.

I claim:
 1. A shooting bow comprising:a main part; a frame on which themain part is mounted; arms, mounted on the main part and convex in adirection of shooting; pulleys disposed at tips of the arms; abowstring, made up from two end spans and one middle span, passing saidpulleys and through a horizontal slotted hole in the frame; and atrigger mechanism mounted on the frame; characterized in that saidshooting bow further comprises a carriage, arranged on said bowstring,and a carriage guide, said frame is manufactured with a frame slot and ahorizontal slotted hole disposed in its forward part, said carriage ismade up with a groove for said bowstring, the carriage guide is arrangedin the frame slot, the carriage is movable along said carriage guide,and the profile of the pulleys satisfies a relationship ΔS₁ =KxΔS₂,wherein:ΔS₁ is a displacement of a centre of mass M₁ to a position M₁ 'of a system including said arms and said pulleys; ΔS₂ is a displacementof a centre of mass M₂ to a position M₂ ' of a system including an arrowand said carriage; and K is a constant for a specific shooting bow ateach instant of straightening of the arms, which is determined from ΔS₁/ΔS₂, the arms satisfying the condition, when a total impulse of saidsystems acting on the main part at a point of fixation of said systems,at each instant of straightening of the arms, approaches zero.
 2. Ashooting bow according to claim 1, characterized in that said groove forsaid bowstring is made up with exit holes, lower edges of which aredisposed below an upper surface of a longitudinal track of the carriage.3. A shooting bow according to claim 1, and further comprising a pullingcord, wherein end spans of said bowstring are bifurcated, a middle spanof said bowstring is made with swellings, and said pulling cord is madewith an elastic rope, secured to the frame and fixed to the tips of thearms.